The function [itex]1/x^2[/itex] grows infinitely large as [itex]x \rightarrow 0[/itex], so you have to break this into two improper integrals:
[tex]\int_{-\infty}^{0} dx/x^2 + \int_{0}^{\infty} dx/x^2[/tex]
You can easily check that both of these integrals diverge to [itex]\infty[/itex].